Volcanic Activity
This core was taken from the Saanich
Inlet, a fjord in southeastern Vancouver
Island, 25 km north of Victoria, British
Columbia. It records exciting events taking
place during our recent Earthâ&#x20AC;&#x2122;s history.

Varve Layer

oldest

This layer is made up of varves. A varve is an annual
layer of sediment, (like a yearly growth ring on trees).
The light layers were deposited during the summer.
They are full of diatoms that grow and bloom during
spring and summer.

f varve s.

The darker layers were deposited during the winter. It
is silt, without diatoms, from a the nearby Cowichan
River.

le o

1

youngest

Does this whitish color remind you of anything? Itâ&#x20AC;&#x2122;s ash!
The ash in this layer comes from the eruption of Mt.
Mazama in Oregon 7,645 years ago. The eruption caused
ash to cover large parts of the Pacific Northwest and
Canada, and resulted in the formation of Crater Lake.

mp

2

Ash Layer

An

ex

a

Leg 169-1034D-7H-1A

208

Era

Period

Cenozoic

Quaternary

Epoch
Holocene

Today

Pleistocene
Pliocene
Miocene

Tertiary

Oligocene
Eocene
Paleocene

Mesozoic

Cretaceous

Late

55 Million Years Ago:
Age of Climate Change Core

Early
Late

Jurassic

Middle
Early

206 Million Years Ago

Climate Change
Your core tells the story of a time in Earth’s history when, over
a period of 20,000 years, temperatures all over the planet
increased by 6°C (11°F). The evidence in this core suggests
that the rapid increase in temperature was caused by gasses
that were released from the ocean floor.

2
1

youngest

Where did the fossils go? The methane released into
the atmosphere dissolved in the oceans making the
seawater more acidic. This caused the calcium
carbonate shells of the planktonic microfossils to
dissolve. This layer is mostly made of clay particles.

At the boundary
Around 55 million years ago, approximately 2,500
billion tons of carbon in the form of methane gas were
released rapidly into the ocean and atmosphere. This
release was caused by a warming event at the bottom
of the ocean. The dramatic line in the core reflects the
dramatic change that took place on Earth.

Paleocene Layer
This layer is made up of thousands and thousands of
fossils from single-celled organisms that thrived in the
ocean over 55 million years ago. At the time, the
ocean temperature was 12 - 16°C (53 - 60°F). The
layer is white because the shells are made of a white
mineral called calcium carbonate.

oldest
os ca r b o
il s
sil c
na
fo s s
lu b . t e m i c r o
org

3

Eocene Layer

m
ciu
C a l // n cf
:
h tt p

Leg 208 -1262B-15H-3

171

Era

Period

Cenozoic

Quaternary

Epoch
Holocene

Today

Pleistocene
Pliocene
Miocene

Tertiary

Oligocene
Eocene
Paleocene

Mesozoic

Cretaceous

Late
Early

65 Million Years Ago:
Age of Mass Extinction Core

Late
Jurassic

Middle
Early

206 Million Years Ago

Mass Extinction
This core shows volcanic activity that took place in
the late Cenozoic about 9 million years ago.
Compare the size and the types of microfossils found
in this layer to those in the older bottom layer. Many
different types of forams became extinct after the
impact, just like the dinosaurs and other organisms.
ers

4

youngest

Tertiary Layer

n if

i

1

Ash Layer
Does this orange/reddish color remind you of
anything? It is the ash and dust that fell to earth after
the meteor hit.

kti

These are tiny glass-like rocks called microtektites.
The meteor hit with such great force that it caused
tons of super heated rock and other debris to fly
high into the sky then rapidly cool to form fine
glassy particles. What rained back down onto
Earth formed this layer.

te s

Tektite Layer

M ic

r ot

e

oldest

Cretaceous Layer
During the time of the dinosaurs, lots of different types
of organisms called foraminifers (forams for short)
lived in the ocean. When they died, their shells settled
to the bottom of the ocean and over time became
fossils. This layer shows how many different sizes and
types of these organisms existed.